This invention relates to fire-retardant polystyrenic compositions.
For many uses, fire-retardant agents must be incorporated into polystyrenic resins, such as polystyrene, styrene-acrylonitrile copolymers (known as SAN resins), acrylonitrile-butadiene-styrene copolymers (known as ABS resins), high impact polystyrenes and the like, to impart fire-resistance to such resins. Organic compounds containing bromine and/or chlorine are frequently employed as fire-retardant agents. However, large amounts of fire-retardant agents are often required to obtain polystyrenic compositions which fulfill specifications relating to flame propagation; and these large amounts are detrimental for other properties of the polystyrenic compositions, such as tensile strength and thermal stability.
With a view toward decreasing the amount of fire-retardant agent which must be added to such resins, the synergistic action of some additives (or synergistic compounds) which, when used alone, do not act as fire-retardant agents, has been contemplated. Organic peroxides have been suggested as synergistic compounds, but they have several drawbacks, more particularly with respect to toxicity and stability.
U.S. Pat. No. 4,092,281 to the above-named inventor discloses certain nitrogen-containing synergistic compounds for use in fire-retardant polystyrenic compositions. The present invention represents an improvement thereover.